Conventionally, a flow path member having a flow path is used for semiconductor manufacturing apparatuses or FPD manufacturing apparatuses. For example, Patent Document 1 describes a dielectric window for a plasma processing apparatus (a flow path member) having a flow path for causing a coolant or a heating medium to flow as an example of the flow path member. The dielectric window for a plasma processing apparatus described in the Patent Document 1 regulates a temperature of the dielectric window for a plasma processing apparatus (a temperature of the flow path member itself) by causing the coolant or the heating medium to flow to the flow path.
The flow path member of the Patent Document 1 has a first dielectric plate (a first substrate), a second dielectric plate (a second substrate) and an adhesive (a bonding member) bonding the first substrate and the second substrate, and a cross section of the flow path in a perpendicular direction to a length direction of the flow path (a direction in which a coolant or a heating medium flows) takes a rectangular shape. Referring to the flow path member of the Patent Document 1, there is described an example in which the adhesive (the bonding member) for bonding the first dielectric plate (the first substrate) and the second dielectric plate (the second substrate) is slightly protruded up to an inner part of the rectangular flow path to bond the first dielectric plate and the second dielectric plate.